Wire perfusion catheter

ABSTRACT

A low profile wire perfusion catheter is disclosed for use in percutaneous transluminal coronary angioplasty. The catheter includes a wire configured to be inserted into a blood vessel. The wire is hollow and defines an axial lumen therein. An inflation balloon is attached directly to the wire and is configured to expand radially outward in response to inflation thereof. Inflow and outflow perfusion ports extend through the wire and communicate with the lumen to allow perfusion of blood across the balloon when the balloon is inflated within a blood vessel. Because the balloon is attached directly to the wire, the catheter has an advantageously low cross-sectional area.

This application is a divisional of Ser. No. 08/813,478 filed Mar. 7,1997 now U.S. Pat. No. 5,800,393.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of balloon catheters, and inparticular relates to a low-profile dilation perfusion catheter.

2. Description of the Related Art

Percutaneous transluminal coronary angioplasty (PCTA) is a procedure fortreating a stenosis or a narrowed region in a coronary artery. PCTA isoften used as an alternative to coronary bypass surgery. A mainadvantage of PCTA is the avoidance of many of the post-operativeproblems associated with such surgery. Moreover, there is a reduction ofmorbidity with the use PCTA over bypass surgery.

In one form, PCTA involves the use of a catheter having an expandableballoon attached to its distal end. The catheter is inserted into anartery, such as into the femoral artery, and advanced transluminallythrough the artery until the balloon is positioned adjacent the narrowedportion of the artery. The balloon is thereafter inflated using aninflation medium that is advanced through a lumen within the catheter.The balloon expands radially outward to displace the obstruction in theartery. If the stenosis is composed primarily of fatty deposits, it ispossible to compress the stenosis against the arterial wall and therebyrestore a portion or all of the original interior diameter of theartery.

Unfortunately, there are certain drawbacks associated with such aprocedure. When the balloon is inflated, it completely occludes theblood flow within the artery. However, it is undesirable to occlude anartery for extended periods of time. The cessation of blood flow causedby the dilated balloon presents a high risk of damage to the portions ofthe body downstream of the occlusion, particularly the heart. Hence, theballoon may only be pressurized for a few seconds at a time in order toavert any damage downstream of the occlusion due to the absence of bloodflow. A balloon catheter treatment thus involves cyclically inflatingand deflating the balloon for short periods of time until the desiredresults are achieved.

SUMMARY OF THE INVENTION

For certain treatments it is desirable to inflate the balloon for longerperiods of time. For instance, a greater inflation period provides astent with a more uniform shape after the balloon is removed, whichpreferably reduces the likelihood of the stent collapsing at a latertime, which may result in undesired complications. Furthermore, anincreased dilation period is also desirable in order to avoid traumathat may occur to arterial walls as a result of the repeated inflationand deflation of the balloon.

Perfusion catheters are other to allow blood flow across an inflatedballoon. Such a catheter has a balloon that is attached to an elongated,hollow catheter body. The hollow body defines a passage that isconfigured to receive a guidewire. The guidewire is percutaneouslyrouted to the site of the stenosis. The catheter is then routed over theguide wire so that the catheter body "rides" over the guide wire to thestenosis site. To solve the problem of the occlusion of blood flowacross the inflated balloon, perfusion ports are employed at locationsproximal and distal of the balloon. The ports communicate with theinflation lumen and thereby place the proximal end of the balloon influid communication with the distal end of the balloon. In this manner,blood is allowed to perfuse across the balloon through the lumen so thatblood flows beyond the balloon even when the balloon is inflated. Thisprovides for longer balloon inflation periods as blood continues to flowacross the inflated balloon.

Unfortunately, such catheters have a high cross-sectional area orprofile. The extra space for perfusion increases the cross-sectionalarea of the catheter. When the catheter is used to deploy an ostialstent (or other type of stent), the profile of the catheter is increasedeven more by the stent, which is-positioned over the balloon and addsmass to the balloon body. Catheters having high profiles are difficultto introduce into the most distal arteries, which have narrow diameters.

In addition, there is a need for a perfusion catheter having a lowprofile in order to allow the catheter to be used in distal arteries andother body lumen having very narrow diameters.

The present invention provides a perfusion balloon catheter having aparticularly low profile. In one aspect of the invention, a ballooncatheter has an axially elongate wire that is suitable for insertioninto a blood vessel. The wire is hollow so that it defines an axiallyextending lumen extending through the wire. An inflation balloon isdirectly attached to the wire to advantageously provide a low profile tothe balloon catheter. This configuration is known as a fixed wireballoon. The balloon is configured to expand radially outward. At leastone influent port extends through the wire on a first side of theballoon so that the effluent port is in fluid communication with thelumen in the wire. At least one effluent port extends through the wireon a second side of the balloon so that the effluent port is also influid communication with the lumen. Blood may advantageously perfuseacross the balloon through the lumen by way of the influent and effluentports. The balloon catheter may be a multi-lobed balloon. Also, anostial stent may be mounted over the balloon.

In one embodiment, at least a portion of the axially elongate wire maybe formed of a porous material. Preferably, the pores are configured toallow the passage of blood through the pores across the balloon. Thepores may replace the influent and effluent perfusion ports to allowblood perfusion across the balloon.

In another aspect of the invention, a catheter includes a first axiallyelongate wire suitable for insertion into a blood vessel. A lumenextends axially through the wire. An inflation lumen is adjacent, andpreferably attached, to the wire. An interior region of the balloon isin fluid communication with the inflation lumen. At least one influentport extends through the wall of the wire proximal of the balloon and atleast one effluent port extends through the wall of the distal of theballoon. The influent and effluent ports allow perfusion of blood intoand out of the wire. The central lumen in the wire allows blood to flowacross the balloon. In one embodiment, a movable wire is locatedadjacent the first axially elongate wire. The movable wire is contiguouswith and slidingly secured to the first axially elongate wire.

In yet another aspect of the invention, a balloon catheter includes anaxially elongate wire suitable for insertion into a blood vessel. Thewire is hollow and defines a lumen extending axially therethrough. Aninflation balloon is directly attached to the wire. The balloon has aproximal end and a distal end, where the proximal end of the inflationballoon integrally forms an elongate catheter shaft that is contiguouswith the wire. Means is provided for perfusing blood through the lumenfrom the proximal end of the balloon to the distal end of the balloon.

These and other features of the invention will now be described withreference to the drawings of preferred embodiments of the wire perfusioncatheter. The illustrated embodiments of the wire perfusion catheter areintended to illustrate, but not to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a balloon catheter in accordance with a firstembodiment of the present invention;

FIG. 2 illustrates the a cross-section of catheter of FIG. 1 in a bodylumen such as an artery;

FIG. 3 illustrates a cross-section along 3--3 of FIG. 1;

FIG. 4 illustrates a balloon catheter of an alternate embodiment of thepresent invention.

FIG. 5 illustrates a balloon catheter of the present invention depictedin an artery with an ostial stent deployed on the balloon;

FIG. 6 illustrates an improved stent having a mesh covering;

FIG. 7 illustrates an improved stent having a hexagonal cross-section;

FIG. 8 illustrates a multi-lobed balloon catheter made in accordancewith the present invention;

FIG. 9 illustrates another embodiment of a balloon catheter at FIG. 8made in accordance with of the present invention;

FIG. 10 is a cross-sectional view along 10--10 of FIG. 9;

FIG. 11 illustrates yet another embodiment of a balloon catheter inaccordance with the present invention;

FIG. 12 is a cross-sectional view of the balloon catheter illustrated inFIG. 10 along 12--12 in FIG. 11;

FIG. 13 illustrates another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a dilation catheter 10 in accordance with a firstembodiment of the present invention. The dilation catheter 10 includes aballoon 12 which has a distal end 14 and a proximal end 16. The balloon12 is mounted directly on an axially elongate wire 20. Thisconfiguration is often referred to as a fixed wire balloon catheterbecause the balloon 12 is mounted directly on the wire 20. Fixed wireballoon catheters have advantage of potentially having a very smallcross-sectional area which may be inserted into very narrow arteries orother lumen in the body. The low profile may even allow use in vesselsand small body lumen such as bile ducts. However, fixed wire balloonsare often less preferable due to the availability of over-the-wireperfusion catheters which allow blood to bypass the balloon, even whilethe balloon is inflated. Such perfusion catheters are known anddescribed in U.S. Pat. Nos. 4,581,017, 5,090,958, 5,160,321, and5,370,617. Perfusion catheters, on the other hand, have been limited tolarger lumen due to the larger catheter cross-section. The presentinvention relates to a method and apparatus to provide perfusion in afixed wire catheter. The construction of fixed wire balloons is known.The balloon 12 is attached to a wire 20 by a suitable means known in theart. The wire 20 extends through the length of the balloon 12 and alsoextends beyond the distal end 14 to define an advance wire 22. Theadvance wire 22 may have a variety of lengths and is configured toassist and guide the insertion of the catheter 10 into a body lumen.

The balloon proximal end 16 and distal end 14 taper to approximately thesize of the wire 20 and integrally form onto the wire 20. An inflationlumen 25 for selective inflation and deflation of the balloon 12 ispositioned adjacent the wire 20 proximally of the balloon.Alternatively, the proximal end 16 may be attached directly to acatheter shaft which surrounds wire 20 and inflation lumen 25, as wellunderstood in the art.

FIG. 2 depicts the cross-section through 2--2 in FIG. 1 and depicts thecatheter in a body lumen in cross-section. As depicted in FIG. 2, thewire 20 extends through the balloon with the balloon mounted on thewire. The inflation lumen 25 enters the balloon 12 at the proximal endand opens into the interior of the balloon 12 to provides inflationmedia for the balloon 12. Such configuration is understood in the art.

FIG. 3 is a cross-section of the balloon through 3--3 of FIG. 1.

Preferably, the balloon 12 is formed of a relatively noncompliantmaterial. For instance, the balloon may be formed of thin polyvinylchloride, polyethylene teraphthalate, nylon, or duralyn. The balloon 12may be manufactured of any wide variety of other medical grade materialsknown to those skilled in the art. The balloon 12 is designed to inflateto a known diameter at a given pressure and has a relatively high burstpoint. The length of the balloon may vary depending upon the particularostial lesion to be treated and the individual patient characteristics.The balloon 12 may take on a variety of different shapes and sizes thatare configured to the stenosis and the particular anatomy of a varietyof blood vessels, such as the carotid artery, and other body lumen.

A radiopaque marker 24 may be located on the balloon 12 or guide wire 20in order to facilitate positioning of the catheter 10 within an artery,as is known in the art. The marker 24 may be manufactured of a varietyof materials known to those skilled in the art, such as platinum, gold,or tungsten alloy.

The wire 20 may be manufactured of any wide variety of medical gradematerials. As discussed below, the type of material for andcharacteristics of the wire 20 may be varied along different portions ofthe wire, such as the portion of the wire that extends through theballoon 12. The length of the wire 20 may vary depending upon thedesired application. For PCTA applications, typical lengths range in thearea of about 120 cm to 140 cm. The wire 20 may have any wide variety ofdiameters configured to fit within the walls of an artery. It will beappreciated that smaller wire diameters can decrease the overall profileof the catheter 10.

In accordance with one embodiment of the invention, the wire 20 ishollow so that it defines a passage 32 (best shown in FIG. 2) thatextends through at least a portion of the wire proximal of the balloon,through the balloon and distal to the balloon. One or more inflowperfusion ports 34 extend through the wire wall near the proximal end 16of the balloon 12. The inflow ports 34 are in fluid communication withthe passage 32 within the wire 20. One or more effluent perfusion ports36 extend through the advance wire 22 wall distal of the distal end 14of the balloon 12 and communicate with the passage 32. The inflow ports34 and effluent ports 36 allow for fluid flow across the balloon 12through the passage 32. The number and size of inflow ports 34 andeffluent ports 36 may be varied according to the application, and remainwithin the scope of the invention.

As shown in FIG. 2, the balloon 12 is positioned within a restrictedarea of an artery 38, such as a stenosis, and inflated using aninflation media that is transferred through the inflation lumen 25.Preferably, the balloon 12 is inflated to a diameter such that theballoon 12 presses against the lumen walls to compress the stenosis. Asshown, in an inflated state, the balloon 12 would completely occlude theflow of blood through the artery 38. The influent ports 34advantageously allow blood to flow into the wire 20, across the balloon12 and out through the effluent ports 36, even when the balloon 12 isinflated. Specifically, blood flows through the influent ports 34 as theblood approaches the proximal end 16 of the inflated balloon 12. Theblood then flows into the passage 32 within the wire 20 and across theballoon 12 where the blood exits the passage 32 through the effluentperfusion ports 36. The blood then flows through the artery vessel.Because the balloon 12 is mounted directly on the wire 20, the catheter10 can have a very low profile so that the catheter 10 may be used indistal arteries having extremely low diameters or for other body lumen.Yet, due to perfusion, the catheter 10 advantageously allows forincreased dilation periods.

FIG. 4 illustrates an alternative embodiment of the present invention.In this embodiment, the effluent ports 34 are replaced or augmented byan axial aperture 40 located at the distal tip of the advance wire 22.In this embodiment, when the balloon 12 is inflated, blood flows throughthe influent ports 34 and across the balloon 12 through the passage 32.The blood then exits the passage 32 through the effluent aperture 40 atthe distal tip of the advance wire 22, and if present, through theeffluent ports 36. Accordingly, the advance wire 22 may contain acombination of both effluent ports 36 on the side of the advance wire 22and an effluent axial aperture 40 at the tip of the advance wire 22.

As an alternative to providing the wire 20 with influent ports 34 andeffluent ports 36, the walls of the wire 20 may be manufactured of aporous material that allows fluid communication between the distal andproximal ends 14 and 16 of the balloon 12. In this embodiment, poresextend through the portions of the wall of the wire 20 that are locatedimmediately proximal and distal of the balloon 12. Preferably, the poresare sufficiently large to allow blood to flow into and out of thepassage 32. The portion of the wire 20 that is located within theballoon 12 may be formed of a non-porous material so that the wireretains the blood as it flows across the balloon 12 and allows pressurein the balloon. Hence, blood flows into the pores at a location proximalof the balloon 12, through the passage 32 across the balloon, and out ofthe pores at a location distal of the balloon 12.

FIG. 5 depicts the catheter of the present invention in combination withan ostial stent 42 to scaffold a flow limiting dissection in a bloodvessel. Other types of stents could also be used. Advantageously, thestent 42 is mounted directly on the balloon 12. The stent 42 increasesthe cross-sectional area of the catheter 10 by adding additionalmaterial to the surface of the balloon. The reduced profile of thepresent invention that is achieved by mounting the balloon 12 directlyto the wire advantageously allows the use of a stent with a perfusioncatheter while providing a reduced cross-sectional area so that thestent 42 may be deployed in narrow lumen.

The stent 42 is deployed in a lumen by first mounting the stent 42 onthe balloon catheter 10. The balloon catheter 10 is then percutaneouslyadvanced to the treatment site. An inflation media is used through theinflation lumen 25 to dilate the balloon, which causes the stent 42 toenlarge to the desired size. The stent 42 remains in the artery afterremoval of the catheter 10 as known in the art. Because of the perfusioncapability via the fixed wire 20, a prolonged stent dilation period ispossible. A prolonged stent dilation period provides more uniformity tothe expanded shape of the stent 42 subsequent to removal of the balloon12. This advantageously reduces the likelihood of atheroma, andpreferably results in-the reduction of thrombus and other complications.Moreover, once the stent 42 is delivered, the operator may remove theballoon 12 with less concern for immediate closure due to thrombus, asthe prolonged dilation period of the stent 42 preferably reduces thelikelihood of the stent 42 losing its expanded shape.

The stent 42 may be deployed within a vessel on either a permanent ortemporary basis. The size of the stent 42 may be varied according to theparticular treatment site and balloon with which the stent 42 is to beused. Any wide variety of material known to those skilled in the art maybe used to manufacture the stent 42. If the stent 42 is to be deployedwithin the artery on a temporary basis, it is envisioned that the stent42 may be manufactured of a material that is configured to eventuallydissolve after a desired period of time within the artery.

Heparin could also be used with the present invention to reduce thelikelihood of occlusion or obstruction thrombus. The balloon 12 could becoated with heparin, as well as portions or all of the wire 20. When thecatheter 10 is used to deploy a stent 40, the stent 40 may also becoated with heparin.

FIG. 6 depicts an alternative embodiment of a stent 28. The stent 28advantageously has a mesh 29 which covers the stent 28 or is integralwith the stent. The mesh 29 advantageously minimizes endothelium fromprotruding through the stent grid. Furthermore, the mesh advantageouslyreduces the rate of restenosis.

FIG. 7 depicts yet another embodiment of a stent 31. The stent 31 has anhexagonal cross-section. The hexagonal shape advantageously providesadded strength over a circular axial cross-section. This hexagonalshape, thereby, decreases the risk of the stent collapsing partially orfully within the artery or other body lumen.

Preferably, the stents 28, 31 of FIGS. 6 and 7 can be made of anyvariety of the known stent materials. The hexagonal stent 31 can be madewith or without the mesh described with reference to FIG. 6.

FIG. 8 illustrates yet another embodiment of the present invention inwhich a multi-lobed dilation balloon 50 is mounted directly on anelongate hollow wire 22. In one embodiment, the multi-lobed balloon is acontinuous balloon having alternating regions of thick 52 and thin 54balloon material. When the balloon 50 is inflated, the thick portions 52do not expand as readily as the thin portions 54. Hence, the dilationcatheter 50 exhibits multiple lobes 54 when inflated. Such a balloon isparticularly useful for dilating tortuous vessels that have acute bends.When inflated, the thin portions 54 advantageously dilate stenoticregions by expanding radially outward to a desired diameter, while thethick portions 52, which are resistant to expansion, do not straightenarterial bends. The thick and thin regions 52 and 54 may have a varietyof different lengths depending upon the desired characteristics of themulti-lobed balloon. The thick portion may comprise restrictions on aballoon or be part of the balloon itself. Alternatively, the lobes maybe formed with individual balloons mounted to the fixed wire 20. Themulti-lobed balloon 50 may be used alone in a PCTA treatment or,alternatively, the balloon may be used in combination with an ostialstent. The profile of the multi-lobed balloon catheter has thecapability of being very small because the multi-lobed balloon ismounted directly to the wire. Furthermore, the influent ports 34 andeffluent ports 36 provide fluid communication between the distal, as inthe previous embodiment, and proximal ends of the multilobed balloon 50to allow blood perfusion across the balloons when inflated. An inflationlumen 60 is provided to inflate the lobes.

Other variations of the multi-lobed balloon or further details areprovided in U.S. Pat. No. 5,019,042, issued May 28, 1991, which isherein incorporated by reference.

FIG. 9 illustrates an additional embodiment for the multi-lobed ballooncatheter 62 for site-specific parenteral delivery of medication ortesting substances to a blood vessel. FIG. 10 is a cross-section of themulti-lobed balloon of FIG. 9. An inflation lumen 70 is in fluidcommunication with the balloons 54. A delivery lumen 72 is in fluidcommunication with delivery apertures 56 positioned between one or moreballoons 54. In addition, in the embodiment depicted in FIGS. 9 and 10,influent perfusion ports 34 are provided proximally of the balloons 54and effluent profusion ports 36 are provided distally of the balloons54. The drug delivery ports 56 may be arranged in a variety of differentmanners. For example, the drug delivery ports 56 could be disposedsymmetrically or randomly between the balloons or could be arranged in asingle line. The particular arrangement of drug delivery ports dependson the desired drug delivery pattern.

The procedure of delivering drugs involves first positioning the balloon62 at a desired drug-delivery site within the blood vessel. The balloon62 is then inflated. Drugs are then introduced at a proximal end of thecatheter into the delivery lumen 72. The drugs travel through thedelivery lumen 72. The substance is expelled through the drug deliveryports 56 and into the blood vessel. Because the balloons 54 are mounteddirectly to the wire 20, the catheter has a low cross-sectional area sothat the catheter may be deployed in arteries and other body lumen withsmall diameters. Prior to delivery of the medication or other substancebetween two lobes of the multi-lobed balloon catheter, the fluid in thebody lumen could be removed via suction on the delivery lumen 72.

FIGS. 11 and 12 illustrate another embodiment of the invention. In thisembodiment, a second wire 80 is movably secured to the wire 20. Thesecond wire 80 may be held to the wire 20 using a thin membrane 82. Themembrane 82 may cover the second wire 80 along its entire length or mayinstead cover portions of the second wire 80 at intervals along thelength thereof. The second wire 80 is located adjacent one side of thehollow wire 20, as shown in FIG. 11. Preferably, the second wire followsa proximal end 83 of the balloon 12, which is mounted directly to thewire 20, so as not to enlarge the cross-sectional area of a balloon 87.In one embodiment the balloon 87 has a depression or slot 89 whichallows the wire 80 to advance. Influent and effluent ports 34 and 36 areprovided in the first wire 22 in the manner described above withreference to the previous embodiments. An inflation lumen 85 in fluidcommunication with the balloon 87 and extending the length of thecatheter, provides inflation media for the balloon 87.

The embodiment illustrated in FIGS. 11 and 12 is particularly suited fordistal arteries or for blood vessel areas that have severe stenosis. Thecatheter is inserted into the blood vessel until the balloon liesadjacent the stenotic area of the vessel. As discussed, the second wire80 follows the proximal end of the balloon so as not to enlarge theprofile of the catheter 10. The balloon 82 is then inflated a desirednumber of times and withdrawn from the stenotic region, while the secondwire 80 is simultaneously advanced beyond the stenotic region. The wire80 is left in place in the blood vessel for a desired period of time toensure that the blood vessel does not collapse. If the vessel collapses,the wire 80 is still in place and provides ready access to the stenoticregion so that another catheter may be passed across the stenotic regionusing the second wire 80.

FIG. 13 depicts yet another embodiment of the present invention. Acatheter 90 has a proximal end 82 and a distal end 84 with the balloon82 mounted directly to a wire 93 to provide a low profile. A manifold 86is located at the proximal end of the catheter 80 and is in fluidcommunication with a hollow passage 95 within the wire 93. One or moreeffluent ports 92 are located distal of the balloon 12. The effluentports 92 are in fluid communication with the passage 32. Preferably, thecatheter 90 may be used for active perfusion or syringe forced flow to alocation of the artery distal of the balloon 87. Blood or medication maybe forced into passage 95 through the manifold 86. The blood ormedication preferably flows through the passage 95 and exits through theeffluent ports 92 at the distal end 84 of the catheter 90. In thismanner, the catheter may be positioned so that the distal end 84 islocated within an artery and the proximal end 82 is located outside thepatient's body. Blood or drugs may be introduced into the passage 95through the manifold 86 and transferred to the distal end 84. The bloodor drugs exit the passage through the effluent ports 92. In addition, anaxial aperture could be provided at the distal end 84 of the wire 13.

An inflation lumen 94 is in fluid communication with the balloon andextends along the catheter to the proximal portion of the catheter toprovide inflation media for the balloon 87.

Although the preferred embodiment of the present invention has disclosedthe features of the invention as applied to these embodiments, it willbe understood that various omissions, substitutions, and changes in theform of the detail of the embodiments illustrated may be made by thoseskilled in the art without departing from the spirit of the presentinvention. Consequently, the scope of the invention should not belimited to the foregoing disclosure, but is to be defined by the claimswhich follow.

What is claimed is:
 1. A stent for placement within a body lumencomprising:a mesh material, said mesh material adapted to form atube-like stent having a hexagonal cross-section.
 2. The stent of claim1, wherein said stent comprises an ostial stent.
 3. The stent of claim2, wherein said stent is coated with heparin.
 4. The stent of claim 1,wherein said stent is expandable and adapted for positioning on aninflation balloon attached to a catheter.
 5. The stent of claim 4,wherein said stent is an ostial stent coated with heparin.